NQR Signal Processing Based On Threshold Method Of Wavelet Transform

Explosive detection technology is important in many fields. It can be used to fight against terrorism, protect security of society, protect battlefield, etc.Improving the efficiency of explosive detection means improving the accuracy of detection, reducing false alarm rate and reducing detection time are the development direction of the explosive detection technology.In a number of explosive detection methods, the nuclear quadrupole resonance (NQR, Nuclear Quadrupole Resonance) technique gets more and more attention by the people because it relys on detecting of elements contained in the explosive. Compared with other detection methods, the advantage of NQR technology is that it can not only determine the presence of explosives, but also determine the types of explosive. However, the NQR signal is extremely weak and it is easy to be submerged in the noise and interference.That is the restriction of NQR technology. If we want to make use of NQR technology in the actual project, we must solve the problems in the NQR signal processing.To extract the NQR signal from the context of noise and interference, it has used a variety of detection algorithms, typical algorithms include:NQR signal of coherent accumulation, spectral analysis, adaptive filtering. However, these algorithms are lack of low detection efficiency, and searching more efficient algorithm is very necessary.Wavelet transform is a time-frequency analysis mothod, it can take nonlinear filtering according to the different characteristics of signal and noise in different scales, so that it can improve signal to noise ratio. Wavelet transform mothod have high time(position) resolution, and is not sensitive to the signal form.This is the traditional filtering methods can not achieve, the wavelet transform method is suitable for weak signal detection and signal location particularly. So we can use the threshold method of wavelet transform to processing the NQR signal.In this paper, research the principle of NQR technology, a wavelet transform method is used in NQR signal processing based on the characteristics of NQR signal. Experiments show that the processing algorithm can effectively eliminate background noise, interference suppression of the ring, and increase the detection efficiency.